The main reason is to avoid the meat during the Tamil month of Purattasi, the rays of the sun weaken and the rains set in. The earth that has heated up in the previous months, soak in the rain and is known to give out heat, which is considered hurtful than the summer heat. It is also believed that the digestion power of individuals is low and there is chance it can take a toll on our digestive system. Hence people avoid consuming meat.
In short individuals maintain a strategic distance from meat as this is the month committed to master Vishnu/Budhan. Rain borne/water borne sickness is more typical in this season. Invulnerability is brought due down to the frail sun beams. It is likewise viewed as rearing season for a few creatures.
The scientific reason is during the month of Purattasi, the rainy season starts at Southern India and there is a sudden climatic change which causes more heat than the heat caused in summer. This leads to various health problems. That is the primary reason why non-veg have been avoided. Many people don’t know the exact science behind this and everybody should know that Hinduism is not just a religion, but also it gives the instructions on how a man should live.